1. Temperature and the Phases of Matter Key Question: What is temperature?

2. GPS: SP3.Students will evaluate the forms and transformations of energy. a.Analyze, evaluate, and apply the principle of conservation of energy and measure the components of work-energy theorem by  describing total energy in a closed system.  relating transformations of potential energy to kinetic energy. f.Analyze the relationship between temperature, internal energy, and work done in a physical system. ESSENTIAL QUESTION? Why does society spend a lot of resources on controlling thermal energy?

3. Temperature and the Phases of Matter  In the Fahrenheit scale, water freezes at 32 degrees and boils at 212 degrees  The Celsius scale divides the difference between the freezing and boiling points of water into 100 degrees (instead of 180).

4. Converting temperatures  A friend in Paris sends you a recipe for a cake.  The French recipe says to bake the cake at a temperature of 200°C for 45 minutes.  At what temperature should you set your oven, which reads temperature in Fahrenheit?

5. Temperature and the Phases of Matter  Temperature measures the kinetic energy per atom due to random motion.

7. Phase changes  When thermal energy is added or subtracted from a material, either the temperature changes, or the phase changes, but usually not both at the same time.

8. Heat and Thermal Energy Key Question:  What is the relationship between heat, temperature, and energy?

9. Heat and Thermal Energy  Temperature is NOT the same as thermal energy.  Thermal energy is energy stored in materials because of differences in temperature.  The thermal energy of an object is the total amount of random kinetic energy for all the atoms in the object.  Remember, temperature measures the random kinetic energy of each atom.

10. Heat and Thermal Energy  Imagine heating a cup of coffee to a temperature of 100°C.  Next think about heating up 1,000 cups of coffee to 100°C.  The final temperature is the same in both cases but the amount of energy needed is very different.

11. Heat and Thermal Energy  Heat is what we call thermal energy that is moving.  The joule (J) is the unit of heat (or thermal energy) used for physics and engineering.  The calorie is a unit of heat often used in chemistry. Heat flows from the hot coffee to the cooler air in the room.

12. Specific Heat  The specific heat is the quantity of heat it takes to raise the temperature of one kilogram of material by one degree Celsius.

13. Specific Heat  The temperature of gold rises quickly compared with water because its specific heat is much less than the specific heat of water.

14. Heat Equation E = mc p (T 2 -T 1 ) Specific heat (J/kg o C) Mass (kg) Heat energy (J) Change in Temperature ( o C)

15. Calculate Heat  One kilogram of water is heated in a microwave oven that delivers 500 watts of heat to the water.  One watt is a flow of energy of one joule per second.  If the water starts at 10°C, how much time does it take to heat up to 100°C?

16. First Law of Thermodynamics  Energy loss is equal to energy gain.

17. Second Law of Thermodynamics

19. Application: The Refrigerator